This is SO frustrating! On the garden board I go to, the pond section, a woman wants to know what she can keep in her two 15g and one 30g. outdoor urns that will eat snails but she doesn't want to mess with filters or anything. She said the lady at the pet store looked at her like she was nuts. I'll bet! -Goldfish and Koi were out because they would be to "labor intensive at this time"
I explained that goldfish would be too large, and that she could do tropicals if she had a filter and heater and let her know that filters were necessary for fish because of the ammonia produced by decaying fish food, waste and plant waste and how that's toxic to fish in that small enviroment. I even offered to email her instructions on how to make a very cheap sponge filter.
Others suggested clown loaches, flathead minnows, a goldfish or two, something called gambusa (I don't know what that is), bettas or weather loaches... out of all the people who responded, only one other person agreed that a filter was necessary.
She's going to get some Gambusa, bettas and try to find some flathead minnows and clownloaches.
What can I say? I tried, I explained it all exactly as it needed to be explained and she chose to ignore my advice along with all the others who suggested those fish.
Anyways, it just ticked me off.

I keep white cloud minnows all year round and have temporarily housed my betta outside for a month with absolutely no problems at all in a 15gal tub outside with no filter no heater and I live in the UK! If its a mature tank enviroment filters arent needed for a small bio-load, I mean are there filters in the wild? My betta came out with A-mazing colours as well. All depends on the bio-load I think and obviosuly I wouldnt reccomend doing it somewhere with an exceptionally cold climate.

I am not agreeing with the pond lady... just pointing out why she might not believe you

Filters are not a requirement in a pond or aquarium.
Before anyone jumps in with rain and rivers- dead end ponds still support fish life... no water in except rain, no water out except evaporation.

I have alittle 2.5g on my desk with no filter... no aerator... nothing...
snails, shrimp and plants... very quiet and serene..._________________Discus Man is gone... I remain... #6... I am not a number I am a free man!

Well, then frankly I'm confused as to why people shell out 300$ for a pond filter, and even that much for an aquarium filter. The filter/pump industry is MASSIVE. People put in all sorts of elaborate schemes to keep the water clean and the fish healthy... I just got back from the fish store and saw an emperor 400 with a pretty high price tag. Why then, if they are unneccessary? It was always my understanding that in our quaint little manmade habbitats, fish in closed spaces, where we are talking about (on average) one gallon of water for every inch of fish as opposed to hundreds of gallons of water for every inch of fish found in nature, we have to have these filters to keep from poisoning our fish with ammonia and other nasties.
Okay, I'll admit when I'm wrong, you guys know a heck of a lot more than me. So does that mean I can just run out right now and buy a load of goldfishes for my new pond without a filter or pump system? Heck, you tell me and I'll go for it, I need something to eat the dead worms out of the bottom

Well, then frankly I'm confused as to why people shell out 300$ for a pond filter, and even that much for an aquarium filter.

Filtration comes down to the simple matter of allowing increased bioload and less frequent water changes. Most people wouldn't be satisfied with the very light stocking level that an unfiltered aquarium can hold and/or the frequency of water changes it would require if you try to push the bioload further up. Since we're already investing money on glass, substrate, lighting, plants, decoration and fish, there's not much of a reason why not to also invest in a good filter so we can have a nice fish population, a reasonable maintenance scheme and better stability in the setup._________________Are you a Fish-HAVER or a Fish-KEEPER?
Success with a fish/tank is measured in YEARS, not months or weeks...

Time to make a confession here. I actually have a tank running with absolutely no electric implements whatsoever. It has no filter, no airpump(though I made add a corner filter just because of extra outlets), no heater, no lights...nothing at all. It houses a pair of bluespotted sunfish. This setup is jam packed with lots of plants/duckweed and some hair algae(I put all the hair algae infested java moss from the 46 gallon here). The fishes spend most of the time hiding somewhere in this. The tank receives filtered light from a windowsill. Waterchanges maybe once every 2 weeks The two fish also aren't fed all that much(usually once a day or less) and the feed is usually live food or frozen bloodworms. Both fish have been growing and sine a few weeks ago the male has been displaying incredible breeding colors. The fish apparently approved this setup as I just discovered fry yesterday!

Someone actually suggested Clown loached for a 15 gallon urn? Ay-yi-yi!
By the way, are there any plants in these urns, or does this lady just get a kick out of having empty water-filled urns sitting in her yard?
Plants would make all the difference in the world.

I have a 300 somthing litre pond. good pH around 7.0-6.5 good for south american fish. I have been toying with the idea of having some fish out there temporarily. its an old pond with some tanon and lots of insects. of course only during the summer months when the pond ususally reaches 24'C.

any ideas?

sounds like this lady is very uninformed and dosen't want to be informed